Amyloid senile plaques and tau neurofibrillary tangles are neuropathologic hallmarks of Alzheimer disease, which may be associated with mild cognitive impairment (MCI) or mood and anxiety symptoms years before the dementia diagnosis. To address this issue, the authors obtained positron emission tomography (PET) scans after intravenous injections of 2-(1-{6-[(2-[fluorine-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile (FDDNP), a molecule that binds to amyloid plaques and neurofibrillary tangles, to determine whether symptoms of depression and anxiety in nondemented subjects were associated with increased FDDNP-PET binding values.